I have an idea, there is a door that is locked and you need the key, you see 3 chests in front of you with a letter. You must follow the clues to conclude which chest is the right one, if you open the wrong one the others will lock for good. Is this possible via scripting?

yes, it is "easily" possible. have a look at Morrowind Scripting for Dummies. you can adapt the first example there to your purposes without much trouble.

Isn't that the one with the Riddle Chest? My scripting knowledge is extremely limited. I am unsure how that helps me.

also how can I do a journal entry upon reading somthing, and then another when I pick up the key?

the riddle chest has code you can adapt for becoming permanently locked. as you are using journal entries, you can deny the player access to the chests before a certain index is reached. to get the journal updated when picking up the key and reading the note, just attach a script to the items in question that looks like this for the book -

short onpcequipshort doonceif ( onpcequip == 1 )        if ( doonce == 0 )                journal ** ; replace "**" with the correct journal index                set doonce to 1        endifendif

for the key -

short doonceif ( doonce == 0 )        journal ** ; replace "**" with the correct journal indexendif