you have 3 main ways of mounting a optic,
a. use the actual scope mount located on the side of your reciever(the little metal box thing on the left side), but this would also require you to buy any ak scope mount. this is the best way, and most solid.
b. mount a scope of your top reciever dust cover. this is the cover you take off to clean the inside guts. You can find optic rails pre-mounted on dust covers that you can buy. This is not so stable, as you know there is no real "locking "feature with the dust cover, not counting the lil hole that fits withthe spring to secure it down.
c. you can purchase a new front handguard that has got rails on the rop and bottom pieces. this is stable, yet this will also make your front end heavy.
Id go with option A to be legit
Drakin