For widescreen support you should grab MGE XE http://www.nexusmods.com/morrowind/mods/41102/?
MGE XE adds lots of nice graphical enhancements and actually makes the gameplay smoother for the most part. You can also create distant land for very far view distances. (this can become quite taxing if set too high) I generally leave the distance at 4, looks best imho.
Code Patch is on the nexus too http://www.nexusmods.com/morrowind/mods/19510/?
You need to extract the contents of the compressed folder to your morrowind directory. So that the codepatch .exe sits next to morrowind.exe
MGE XE and the code patch arent your regular sort of mod. They don't contain a plugin and assets. MCP alters the games executable file and MGE basically straps itself to the executable. You should read both of the readme's contained within each mod before using them. They are however both pretty straight forward to install really. Drag and drop the contents from the archive to the morrowind directory.
As you're new to modding it may be worth mentioning that its recommended to move Morrowind out of the program files if you have UCP in windows active. Can cause all kinds of permission problems when installing mods.
I can't say anything for Rebirth and MGSO, neither are really to my taste so don't use them.
I do suggest getting the Patch Project http://www.uesp.net/wiki/Tes3Mod:Morrowind_Patch_Project
I also recommend getting the latest WyreMash Fork for installing mods and managing your load order and whatnot. http://www.uesp.net/wiki/Tes3Mod:Wrye_Mash
Again, read the readme.
Yeah its a lot to take in I know.