if you watch some of the FT tutorials, you can see they join wing parts together regularly. You just need to but the parts together and glue. In some cases you would also want to extend some sort of structure/spar across the join to make sure it is strong enough to not break.
without some more specific details, it would be hard to tell you more exact steps.
that said - hopefully you mean first self designed plane, not first plane built/flown (you don't want to learn to fly with a plane you don't know can fly well - as you won't be able to tell if it is user error or the plane causing the crashes).
