What is an "A frame"? Do you mean a Ford Model A 1928-31? Or do you mean a General Motors "A" body (Chevelle, Skylark, ect)?
If it's the Model A you change camber by bending the axle, and of course it's largely left as is. Caster by leaning the axle back or forward, what sort of four bar or wishbones are you using? With a four bar with adjustable ends you lengthen the lower bars or shorten the upper ones to gain caster, just the opposite to lessen the caster. If it's a split wishbone or wishbone you need to drop the rear mounting at the frame to gain caster, raise the mounting to lessen the caster. Setting toe is simply measuring the distance from tire to tire in the front, then in the rear and adjust the tie rod by screwing it in or out of the tie rod ends to change that distance. A 1/8 to a 1/4" toe in is your typical toe for a solid axle front end.
An "A" body, refer to LATECH's post.
Do you have the tools to know what caster and camber you have?