When you put the first side of the tire on the rim, that went easily enough didn't it? The second side will do the same if you get the tube and first side of the tire out of the space that the second side needs to go on the rim.

Once you figure out how to do that, you'll be able to install most any bicycle tire on any rim without a lever or tools. And with a little more practice, you can remove the tire with just your fingers.

However that rim isn't one that's going to give a lot of slack. So you might just need to get a tire jack for the short term. And continue to work toward that nirvana of no tools during the next couple dozen times you have to remove the tire from the rim.