Here you see (nearly) all the listed things you need, with exception of the sewing machine, belt and green thread.

You start by drawing the shape of the strawberry. The smartest thing to do is to make a pattern on paper first. But I decided not to xP
I was first going to give the bag strokes allong the sides, so there's more space inside, that's what the second line is for, but I erased it later, so just draw it the size you like =) Fold your felt in half, so that when you cut it, you get 2 strawberry shapes.

Draw the leaves on the green felt. The best way to do this is by cutting out your strawberries and line the top of them on your green felt. you can add leaves and stalk then.
Cut these shapes out too.

sew the leaves onto the strawberries. I just stitched them all around, through the bottom of the stalk.

Tadah.

The next step probably is the trickiest one. getting that zipper stuck in the right place!.
you should fold the edge of your fabric just a tiny bit to the inside, lay the zipper underneath it and stitch over it. (pin the stalk down, that's easier)
Repeat this on the other strawberry!

TIP: to make it extra sturdy, sew over it again on the inside.

Now you can breathe calmly again.
Turn your strawberry inside out.
sew along the edges, leaving 5mm distance.

Leave opening for the belt!

Add the seeds with your fabric paint.
Read the instructions before using it. Mine is supossed to dry for 24h.
If you want to do this step at the end, you can just do that.

your belt probably is too short, so you will want to make it longer.
For this you can use the felt you have left. Either red or green or any other colored felt you own.
The first thing to do it cut you belt in half. I did it this way: close your belt in a random hole and cut in the opposite side of the buckle. (so you can still change the length of it afterwards)
Make a stroke with the same width as your belt and make it as long as you want to, length doesn't really matter a lot. You can make it too long at first, sew it onto your belt, try it on and cut pieces of 'till it perfect.
But getting this strokes on perfectly may get tricky. You want to fold it inside out around your belt. Then sew over the piece where the belt and the felt overlap. Now, pay attention to this, sew the open side shut, close to the belt.
Not TOO tight because you will have to turn it inside out again.

MAKE SURE YOUR STROKES ARE WIDE ENOUGH.
Mine weren't so it was a pain.

Now sew the other end to the strawberry..
You do this by turning the strawberry inside out and then stick the belt through the INSIDE of the strawberry so you can see a piece sticking out on the side that is out now.
With inside I mean the side that is the original outside when your strawberry is folded correctly.

Voila! You have created a cute bag with multiple functions!
Be proud and enjoy!