Since this an older RPGMaker game you can use cheat engine to make changes, though it's a not as simple as most save editors. One big warning with cheat engine, you're editing RAM directly, which can really mess up programs. Your computer should be fine, but a restart of the program or computer may be needed if you poke around at the wrong values. Changing stats in RPGMaker games is pretty safe, but doing fancier things should be done with caution.
So, to use cheat engine first you need to install the program (obviously), then run the game and cheat engine.
Make a backup of your save just in case, then load it in game. In cheat engine click on the selection button (a monitor with a magnifying glass on it, it should be flashing red in the upper left corner). Then select the game in the list that pops up.
Next you look at what the value of the thing you want to change is, then multiply it by 2 and add 1 (this is specific to older RPGMaker games), type that value into the scan text box. Gold is the easy example, so we'll go with that. If your gold is 1000, then you type 2001 (2*1000+1), then click first scan. This will bring a list of values up in the address list on the left. There will likely be many of them, so you need to narrow it down. So, go and do something to change the value (buy an item, sell an item, exc). Then use the formula, type that new value in and click next scan (this only checks the list of values you already found as opposed to all the values). For the gold example if your new gold is 800, you'd type in 1601.
Repeat this until you have 1 address left (sometimes 2, depending on how they made the game), then double click on it (both of them if there are 2). This will add it to the list in the bottom of the window. There you can select the value and change it, using the formula in reverse. So, for the gold example, if you wanted to have 10,000 gold you'd put in 20,001. After you've made the changes you want, just close cheat engine and save your game.
Also, the addresses used change every time you open the game or load a save file, so all the scanning and edits need to be done from the start any time you want to make changes.