so i am a level 15 and whenever i try to upgrade a perk on destruction, it wont let me, and i have to upgrading something like locking or whatever... i have upgraded part of the tree though, any help? much appreciated, thanks

Is your skill level high enough? To unlock a perk one needs to have all the previous perks on the particular branch unlocked AND have the minimum skill level needed for the perk.

umm i am a level 15 idk what you mean... i have all the previous perks for it, how do i finf out what the minimum skill level for it is?

The destruction perks, like all perks, have skill requirements to unlock the middle/higher perks. Some also have perk prerequisites lower on the tree. If you hover your cursor over the perk you want, it'll show you the skill level in that skill required and your current unmodified skill in that skill.

Here is a small section of UESP wiki that shows the destruction perks. It shows the skill required and any perks needed to get each perk - http://www.uesp.net/wiki/Skyrim:Destruction#Perks

The Rune Master perk, for example, requires a destruction skill of 40 and Apprentice Destruction as a prerequisite.

It's mentioned on the tree: http://static-3.nexusmods.com/15/mods/110/images/19019-1-1340063150.gif just under the skill you want to choose. On the left your current level, on the right the required level to upgrade.

ok, i understand, thanks all