Please help joining yarns

Greetings fellow knit-nuts! I’ve recently joined your ranks… and thrilled to be here!

I am working on a lovely afghan for my mother, and I want to do the same color border all around with a different color in the center. Problem I’m having is joining the two color yarns from border to center so there isn’t a long gap traveling through my project. Had to unravel 6 hours of work yesterday when I discovered I’d done it wrong. Please help!! I am sure there is such a simple solution to this but I’m having trouble educating myself on this one.

Any words of wisdom will be greatly appreciated!!
Thanks so much,

Let me see if I have this right. You want, for example a blue border, yellow center, and then blue border? It sounds like you pretty much have to use intarsia-type joining.

For example, knit across with blue, drop the blue yarn but don’t cut it off, knit across with the yellow, then attach another ball of blue for the other border.

When you change colors, insert your needle for the next stitch, then make sure that the old color is being held across the back–secure it with your left hand, then knit the new color. This will prevent a hole.

And by the way–welcome!!