How do I find data in separate worksheets and normalise?
 

I have several spreadsheets with userid information and department registers,
that is, the department that the user is allocated to. I need to make a
correlation between the information to obtain all of the information on one
sheet (userid, department, username). Basically, userid and department on
one sheet and userid and name on another sheet. Compounded by full userid
list and last login userid list on another sheet.
I have tried vlookup and nested if's but cannot seem to make anything work.
If anyone has any ideas it would be greatly appreciated!