Please don't consider yourself 'dumb' for asking question(s). Everybody here started out new at one time, even though some of us tend to forget occasionally.
Please post back with details as suggested and let's see if we can provide assistance.
First though, check your radiator for being clogged with debris. Flush gently with water hose from both sides repeatedly until water runs clear from both sides. Don't use a nozzle as will bend fins. A hose-end sprayer (like for lawns) filled with liquid detergent might help.
I've suggested on here--and respondents indicate works in their own use--installing a cheap $1 blue/white/green/pink coarse fiberglass HVAC filter ahead of your radiator (or radiator screen is so equipped and still present). The HVAC techs in my area call these things useless cat-hair catchers, but works great on Kubotas. Avoid the type with metallic grid as may short a battery or rub a hose or wire.
This is especially handy if brushhogging taller heavy growth with intense seed heads, tiny leaves, and lots of dust.
When you see your temp gauge climb a notch or two stop and remove the newly-installed prefilter and shake it out, reinstall it, keep going.
On my brushhog machine a 20x20x1 filter works great. You can always trim it to fit if desired, but I tend to make it fit by folding and overlapping. When it gets too dirty, replace it.
If we get past the possibility of a clogged radiator, then with your additional details maybe we can get focused in on what other problem(s) might exist. With a bit of back-and-forth I bet you can find a solution.
Please post back your experiences--and your additional questions if any--so we may all learn together.
