I make my frist mini coro plane
!
but the problem is how to mount landing gear in plane

Use plywood

can you send some pic of mount ??

As stated above, fix a piece of ply with cyno. Then fix landing gear on it.
You can also pass the nuts through ply and coro,then add a piece of gift card above the bottom plate of fuselarge, and then tight the nuts above the plastic cards. This will help the ply to remain on fuse in harsh landings, and gift card will prevent to tear the coro.
sorry for the blur image.

As manoj said,

you can also use a thicker ply block, based on the size of your plane, maybe 6-8 mm in your case, mount the block inside the fuse and tether from three sides, bottom, left and right using epoxy/ca and use screws to fasten. Use small screws with credit card plates, to avoid coro tearing as suggested by Manoj

If still in doubt, meet us tomorrow at the field, and you can analyse the way rcboltz have done for most builds.

thank you
sir
i will come to gurgaon next saturday .
sorry for my english ..
so weak .