You're selling two gifts for one key? Hit 'create trade', then select 'batch', select the two gifts, select what you want, select how many batches (I.E. how many copies of 2 gifts you're selling) and click go. For an example of what it'll look like to the end user, see this (Note, I'll close this trade in ~ 24 hours, I made it just to show you an example):-

http://dispenser.tf/trade/111775/

Four gift version is identical, but, if you're planning to sell the same gift, don't bother utilizing that as anyone can just select more "Batches to purchase" and get it all in the same trade, this gives the end user the ability to choose how many s/he wants.