IT WON'T LET ME. I'VE BEEN TRYING ALL DAY.

Do a favor for a Jarl. Then talk to the steward.

Only holds that don't have available houses will let you buy land.

You can buy land in dawnstar, morthal, or falkreath, i wld suggest falkreath the land is the best and it has a nice view with the lake 4 my taste morthal is to swampy and dawnstar is to snowy but its ur choise

I've done all the favors for the jarls. I haven't run into the curriors. Nor have I had the option of asking to buy land. What i am doing wrong?

Become Thane, and these quests open houses; waking Nightmare (dawnstar, must also be at least 21-23 in level), Laid to rest (morthal, no level requirement). Ask the Jarl about purchasing land, then ask the steward of the hold.

Start with the Jarl of Falkreach, for that is the one that the messenger sends you to begin with. If you have already started any of the "Helping My People" quest for him, you have to finish that. That was the problem I had with one of my characters. After you finish that, the option should open up. Hope that helps.

I always get Lakeview on new characters, straight away. I'm not Thane of that hold, but just did 3 favor quests. Ask at the Inn for any work, that's what I kept doing. At some point, if you haven't already, just go and meet the Jarl. Go through all dialogue choices, ask him for work. When he says that he likes you then he should mention allowing you to purchase property in his Hold. Then talk to the Steward.
Morthal has always been fairly straight forward for me as well. Same sort of thing, though I accidentally end up becoming Thane first as, IMO, it's just so easy with that one

For Lakeview it's fairly easy. Usually around level 8 I get a letter delivered from the Jarl asking to go see him. I do and he tells me to clear out some bandits that double-crossed him. I do and he says thanks and his steward has some land for sell for 5,000 gold. That's it. No other quests. No Thane. That's it for Lakeview.

I know the other houses require more to be done, one even a Daedric quest that can't even be started until you are higher level. No spoilers here though.

Your level matters as well. You cannot buy land in the Pale until you are level 22 or 23. Until then the option just will not be there. I forget what the level requirement is for the land in Morthal. Lakeview is the lowest though, as LeBurns said, it is level 8 or so.

I can't seem to get the Falkreath plot of land either. As far as I can tell I've exhausted all the side quests in the place. I remember one of my other little project charcters getting a note from the jarl (which cause I was trying to do some Dark Brothergood stuff I never followed up on) but if my main guy ever got the note I don't remember it. I certaintly haven't gotten a note since I had Hearthfire installed.

Does that character have any of the http://www.uesp.net/wiki/Skyrim:Rare_Gifts still do do in the journal? Anything like that can stuff up buying the land. The letter the courier was to give you takes the place of the fetch the mead quest, you can only have one rare gift quest active, so if you already have one in the journal, you would have to complete it. Other than that has that character killed Siddgeir's housecarl as a Dark Brotherhood quest? If you have made an enemy of Siddgeir and he is still Jarl, he will not send you the letter, because he is not going to sell you any land. If you are playing on the PC you could cheat your way around that problem.

Thanks for the help I'm going to follow up on this rare gift thing I think it might be the Mammoth Tusk or the Song of the Alchemists.

Yes I think that was the ticket I'm on my way to Embershard now to eliminate some bandits. Thanks for the tip I doubt I'd have ever figured that out without some outside help. They really need to patch that though. This is a really round about way to be able to enjoy a DLC that I purchased.

Well there are three houses, so even if you never asked, you could still enjoy the other two. And you play long enough you might eventually get all the quests cleared in the journal. Took me well over 6 months to go get that mammoth tusk, even though i got the quest the first day I played, and probably it was another week before I suddenly found out the Jarl in Falkreath actually had different dialogue. Took forever for my first character to become Thane of Falkreath. I had trouble becoming Thane in a few holds, so just thought they had put one there I could not become Thane for, just to drive me nuts!