Hold on there Tom. It sounds like you have one of the clamp style mounts. Check your instructions carefully and you will probably see that there are two flat metal bars with holes near the ends. The holes in the bars will match the holes in the mount. You put the engine on the mount, put the bars on top of the the engine's mounting lugs and then tighten the bars down to clamp the engine into place.

These mounts are very common in trainer ARFs.

Jim