Lay it flat, use a spray bottle with about 10% dawn dishsoap and water.
Spray genrously and let sit.
If the tires have been on the rim for awhile it's going to take some effort.
You might want to go around the rim with a deadblow (plastic) hammer or similar to start breaking the bead seal.
You can lay a 1x4 over the rim where your working to keep from smacking your rim.
Your going to have to do both sides.
Do both sides First.
I usually lay a piece of plywood down under a manual bead breaker.
Just makes it more stable and less likely to damage something.
Make sure you take your valve core is out of the stem too.
Break both beads first.
If the bead breaker doesnt work there are other methods to break a bead seal, but they start getting kind of sketchy.
Most rims are designed to pull the outer bead over the front side first, then the inner bead over the front/outside.
You can tell by the softer (often narrower) radius near the rim seat.
You can find rim protectors that slip onto the edge of the rim.
I would seriously suggest using them unless you hate your rims.
Or you can use vinyl edge trim thats wide enough to slip over the edge of the rim.
THREE tire spoons, not two. Trust me. THREE SPOONS.
You get one in (small bites), get your second one in then use your third spoon to lock it into place.
Stic it in as close as you can, swing it over the second spoon and hold it with your knee.
Then you leap frog the first spoon and take another small bite.
If you take too big of a bite, you will just undo everything you already did.
Repeat.
Once your about halfway you will feel the pressure ease and might be able to just pull it by hand the rest of the way.
Locking the spoons with a third lever helps prevent getting slapped in the face.
(I made a custom set of 36" ones)
The shorter your sidewall in relation to your rim, the more of a fight your in for.
Once you get the tire off wash your rim, and scrub the bead seat on the rim.
Steel wool on a steel rim is fine but use a plastic scrubby on Aluminum.
On a steel rim you can knock the rust down with mid to fine sandpaper.
Your just knocking rust off, not trying to polish it.
DONT sand aluminum ones.
Good time to look for cracks, pitted metal on aluminum or cracking welds on steel rims.
My solution now is to be grateful I DON'T have to hand change tires routinely like I used to.
At one point I could do a truck tire off and back on in about 15 minutes.
ps, the dots/circles on the tires are alignment indicators.