This is the one I recently made for my sister. There are tons of tutorials out there, but most of them use velcro straps. I like to use ribbon mainly because for some strange reason my newborns cry at the sound of velcro being undone.
So first you want two cute pieces of fabric about a yard of each (if you like ugly fabric it will work too). Lay them on top of each other right sides together. If you are a measuring, cutting evenly, following directions kinda girl then at this point you want to get out a plate or bowl and round the corners. Unfortunately for my sister I like to just kind start sewing. But hey I did at least pin the ric rac in place. I pinned because I care.
Okay, So your fabric is cut and you now need to put you ric rac in place. If you are not planning on using ric rac then don't pin it in place (I guess you may have already known that.)
Have the ric rac off the edge where it starts so the end will get all sewn down. If you were on of those awesome cutting people then you would have cut off the white edge there.
If you cut off you corners then just have the ric rac follow around the corner. And pin all three layers in place and sew them together leaving a hold so you can turn it right side out.
See look there's the hole.
Then top stitch to sew it closed.
Sorry I have no pictures of it on a car seat BECAUSE I don't have one in my house right now. Sad. I need a baby. A little baby who needs a little car seat and protection from the wind and cold and people.
Wellllll. I think that is everything.
Travel Blanket... Check
Nursing Cover... Check
Wipey Case... Check
and last but not least Car Seat Tent Cover Thingy... Check