Patchwork Blanket Pattern

I want to make my friend a blanket for christmas, unfortunately she is also my housemate. So I figured I would knit a blanket that I could make by knitting one square at a time so she wouldn’t catch on to what I was doing, and then join them all together into a blanket.

I am pretty new to knitting though and I don’t know how I will join the squares and I can’t seem to find a pattern that describes the process. Has anyone made a pattern similar to this that will also take me through combining the squares, or alternatively can someone just describe how to do it?

Thanks in advance!!

Here are a couple patterns, hopefully you get some ideas: