It would really help if you stated the manufacture of the 1088. So I'm going to guess it's a Crosman.
See the link below
See the related link at the bottom of this page to see the Crosman 1088 parts manual.
see the link below for the Owners manual.
Crosman has a web page for their owners manuals and part list. See the attached web page. you will find your 1088 listed about half way down on the page. The parts last will give you an exploded view of the gun. See the related link
see the link below for the owners manual
see the link below
The 1088 has a round tin packaged with the pistol. It looks like a pellet tin but if you look close at it, it says (100 pellets and 100 BB's) both are in the same tin can.
check: http://stevespages.com/page7b.htm
Best left to a trained gunmsith
Follow instructions in owner's manual.
Best thing to do is to get a gunsmith to help you.
Best left to a trained gunsmith.
It will shoot pellets or bb's. They normally use an air cartridge.