Though I agree with the fact that adding another female would be much better, I disagree with 'you have a lot of space' - you do not. Angels with dwarf gouramies is, in itself, risky. Looking at the, active, golden barbs you have, the rummies that are going to get eaten (and are in too small a group) and the plec (which is probably a large-growing one - and deffinately high waste-producing), you'd be better off returning the dwarf gouramies altogether. You need to increase the school size for the tetras and consider what you're going to do about the possible future angel-dwarf clash that will occur if those angels breed...
edit: Breeding them is not possible in a community tank like yours. A heavily planted tank with only some bottom dwellers and very weak current may work but a seperate breeding tank (prefferable) with a sponge filter, heater, bare bottom, tight-fitting cover and lights. Plus tiny food ready for when the fry are free-swimming (infusoria at first, then baby brine shrimp, microworms, vinegar eels, egg-layer liquid foods or, possibly, messy egg-yolk and, finaly, later powdered and crushed flake). You also need to consider the necessity for a grow-out tank and what you'll do with all the fry and, of course, take into consideration that these are not very forgiving fish and won't tolerate terrible water quality as a result of over-stocking/over-crowding fry. Dwarf gouramies are otherwise simple to breed and will do so readily at a temp. of about 80 deg F in water with a pH between 6 and 8 and if there are some floating plants (or other objects - eg: styrofoam cup cut lengthways!) in the water and nearly no current. Clean water and minnimal stress are, of course, essential. Conditioning with live foods, at the same time seperating the male from the female, also helps.