Auto population on a form

I would like to Know which formulas to use for the attached example.

I need to create a form that auto populates all other information to the right of the ref number.

So if I add a ref number i.e. 101 then the the adjacent three columns should take info from the second sheet.

and also how to copy the formula to other rows so that the info relates to each line and relevant ref number.

I can do dropdown for the ref number but need to know the rest!

Many thanks

Clair