Working into the foundation chain is about the trickiest thing to do in crochet and its the bit you need to start with to do anything in rows! The other issue with chains is that they often don't have the same stretch as the rest of the fabric which can lead to a tight hem or a distorted blanket.
Luckily there is another way. You can create your foundation chain and first row all in one if you know how. Genius!
The first row can be made in any stitch but this photo tutorial shows how to with the double crochet (US single crochet) then explains how to adapt it for the taller stitches.
How to work a foundation double crochet (fdc)
(US foundation single crochet (fsc))
1/ Chain 2
2/ Insert hook into 2nd ch from the hook, yarn over and pull up a loop through the chain. This action links the stitch.
3/ Yarn over and pull through the first loop on the hook. This creates the chain portion, hang on to this because you are going to need to know where it is in a moment.
4/ Yarn over again and pull through both loops on the hook. This creates the stitch. (notice how I am holding on the chain section in the photo)
5/ Insert your hook into the chain part of the last stitch, yarn over and pull up a loop. This links the stitch
6/ Yarn over and through one loop to create the chain. Again hold onto this because you need to know where it is.
7 /Yarn over and pull through both loops on the hook to create the stitch.
Repeat steps 5-7 until you have enough stitches in your foundation row.
I like to repeat to myself the following to remember where I am "once to link it, once to chain it, through everything to make the stitch"
Once you've mastered it in double crochet (US single crochet) you'll be ready to try it with all the stitches!
To adapt it for other stitches you'd adjust the chain you make in step 1 to be the usual turning chain for the stitch plus 1. You'd then yarn over (one or more times) before inserting your hook in step 2 and 5. Then steps 4 and 7 you'd make the stitch as you normally would, so for a half treble/ (US half double crochet) you'd pull through all three loops on the hook, and for a treble (US double crochet) you'd yarn over and pull through two loops twice, and so on.
You can pretty much substitute this technique in any time you are asked to create a chain with a row of stitches into it. Just be aware that lacey patterns might be quite tricky to start this way and sometimes in garments the foundation chain gives structure to a seam so think about that before substituting.