So im trying to add an primary key and a foreign key to my table, but i just can't seem to get it to work. i've checked the forums already and other places but it didn't answer my problem. So here is my table:

<http://puu.sh/mVW7D/5986e08daa.png>
im trying to get VeiederID as my foreing key and keep studentnr as primary

but ive tryied to "alter table" and add the foreing key as constraint, but i might be doing it wrong, im very new to mysql. any help is appirciated