Hopefully this helps, it's a very simple snowflake in a few steps. I haven't written every single step but you should hopefully be able to follow along from the screenshots. There are many ways this could be achieved and variations, play around with it and share your results.
1- Use a star shape and adjust the settings as in screenshot
2- Use the rounded rectangle tool to create a line that will go down the middle (adjust settings)
3- Duplicate shapes (CMD + J) and rotate into place
4- Again duplicate one of those lines and make them smaller and move in to place
5- Repeat and move shapes into place and then groups these together in the layers panel (CMD + G)
6- Duplicate this group and rate and put in place. There you are a simple snowflake
