Do yourself a favor and give that piece of junk to somebody you really don't like.

That is a varmit scope intended for use on a specialized gun for long-range shooting. In general, higher power scopes demand the higest optical quality glass and construction. Yours, frankly, is the lowest quality glass and construction. Your friend did you no favors by giving you that scope, trust me. It is completely mismatched for a muzzleloader too.

Put some iron sights on the gun and learn to shoot them while you save your money for something better.

There are few shortcuts in the optics world. In general you get what you pay for. You paid nothing for that scope and got junk - no harm in that because at this point you haven't lost anything.

Servicable, reliable optics don't need to cost a fortune. The last 4 scopes I purchased were either used or new on ebay. I did not pay more than $200.00 for any of these - in fact the Nikon Pro-Staff was less than $100 and so was the used Burris. They have performed flawlessly to date

Nikon Buckmaster 3X9X40 (excellent used condition)
Nikon Pro-Staff 2X7X32 (new in the box)
Burris Fullfield II 3X9X40 ballistic plex (good used condition - some ring marks)
Bushnell Elite 3200 4X12X40 ballistic plex (new in the box)