How to create patch from altered ROM?

[WorkoutGamer13]

So I'm very new to this, and I've spent some time looking around to find the answers I seek but to no avail.  I have already modified both of the Genesis Shining Force games, but they were alterations done directly onto the ROM itself.  How can I create a "patch" of the changes I've made for the games to share them? 

I'm a huge fan of strategy games and I spent a great deal of time making precise changes to make the games more fun and versatile because they have such a large cast of characters.  I wanted to make it more fun by giving the player specific reasons to pick X character over Y for Z battle.  If I have somehow missed that information like say subtracting the differences between a modified ROM and the original and taking the difference into another file, I will freely admit I had overlooked it.  If not, I would appreciate some pointers.  Thanks to everyone in advance.

[henke37]

Find a premade tool to create the patch. Preferably one using a good file format for the patch.

[STARWIN]

Thinking involved: go to Utilities section and set a category filter "Patching".

No thinking involved: use http://www.romhacking.net/utilities/240/

Are your changes about making the game harder or just different? I could never get into shining force games as if I recall they don't really care about the player losing, or something like that.

[henke37]

IPS is not considered a good format. It doesn't check that the input file is correct and it doesn't deal with moved data well.

[puzzledude]

So I'm very new to this, and I've spent some time looking around to find the answers I seek but to no avail.  I have already modified both of the Genesis Shining Force games, but they were alterations done directly onto the ROM itself.  How can I create a "patch" of the changes I've made for the games to share them? 

I'm a huge fan of strategy games and I spent a great deal of time making precise changes to make the games more fun and versatile because they have such a large cast of characters.  I wanted to make it more fun by giving the player specific reasons to pick X character over Y for Z battle.  If I have somehow missed that information like say subtracting the differences between a modified ROM and the original and taking the difference into another file, I will freely admit I had overlooked it.  If not, I would appreciate some pointers.  Thanks to everyone in advance.

Get this utility
http://www.romhacking.net/utilities/519/

Create patch by selecting the patch name (with .ups extension), original rom and the modified rom. The patch will be autocreated and will contain all the changes between original and changed. Others will then patch the ups to original rom (ups also prevents the false patching, to a false original rom).