To play with sprite memory, usually you will reserve $0200 for sprite ram. Then, you will want to play with the memory at $0200 to get a feel for how sprites work. every 4 bytes is a sprite. The first byte is the Y coordinate, the second byte is which tile to use from your nametable, the third byte consists of attributes (flip is all I've used in my own game so far), the fourth byte is the X coordinate. Once you've put in some test values into the first 4-byte entry at $0200, call the below function "sprite_update_all" to stuff the $0200 page into sprite OAM. In the below code, the "sprite" label is equal to $0200. Make sure when you call sprite_update_all you do it either while drawing is turned off, or during vblank. You may also want to call sprite_clear_all before you play with your sprite page, to hide any garbage sprites that may already be in RAM.
Code:
;note this is CA65 syntax, your anonymous labels in your preferred assembler may be slightly different.
sprite_update_all:
lda #>(sprite)
sta $4014
rts
sprite_clear_all:
lda #$ff
ldx #$00
: sta sprite, x
inx
bne :-
rts
Good luck!
Later on once you're used to the basics---the above advice concerning meta sprites and updating the entire sprite page will become more useful if you move on to a game engine. But for learning, twiddling with a few bytes is a good way to proceed.
*edit* I forgot an important detail. The "attributes" byte of each sprite contains not only information such as how to flip the sprite, but also its color attribute. I believe the low 2 bits are the color attribute. Probably when you're first testing this stuff that won't matter, just write 0 to this byte for now (use the first 4 colors in your sprite palette, do not flip, do not hide behind background).
