Step 1:
Prefold in half four times.

Step 8:
Prefold over these four lines.

Step 6:
Squash-fold, see arrow

Step 11:
Fold in half.

Step 10:
Use the prefolded lines as help.

Step 9:
Fold on the four corners. All eight sides are the same length.

Step 5:
Fold over the prefolded lines.

Step 7:
Fold over these two lines.

Step 3:
Fold both corners inwards.

Step 2:
Fold over these two lines.

Step 4:
Turn the model.

Step 12:
Fold in half one more time and curve the tip.

Step 13:
Make pleats, use the prefolded lines as help.

Done!
This is an Origami video tutorial for folding the umbrella:

Pictures: Fashion doll in summer outfit on a rainy day, holding a paper dollhouse umbrella