When it says 'join', in this case I'm fairly certain it is asking you to join the yarn and begin working on the stitches that up till now have been on hold. The way you put your stitches on hold sounds fine - as long as you have the needle in in such a way that you are ready to work a right side row you will be fine.
To join the yarn back in, all you need to do is start knitting with it! Hold the loose tail end of the yarn to the back of your work and knit the first stitch with the working yarn. This stitch will be reeeeally loose for the time being, but there's a trick you can do to tighten it up. Knit the first stitch as I said, and then for the next 3 or 4 stitches, hold the tail end of the yarn AND the working end of the yarn together and knit those next few stitches with both ends held together. This will tighten up that first stitch nicely, and it will also weave in the loose end at the same time. From there on, you can drop the tail end of the yarn and just keep on with only the working yarn. It says to knit to the end of the right side row, so all you do is complete the rest of that row using knit stitches and then move onto the next instruction.
Ask back if you have more questions or if this answer wasn't clear. We want to help you finish that first project!!!!