Passing data from one form to another on button click

Hello

I have a form named FORM_PURCHASE and within this form i have some empty fields which i want populating from another form\database table.

So the user clicks a button on my form which open anew form named FORM_SUPPLIERS and this form contains many different records for which the use will select one and then maybe click a button which i then want the information displayed on this form to be automatically entered into the corresponding fields in my form FORM_PURCHASE

I hope this makes sense.