My character is not sure about which side to choose as the imperials tried to execute her but she thinks she should side with her own race. How ever she escaped with the storm cloakes with the help of Ralof. Help her decide who to join.

The empire isn't a race per se. It encompasses many races and there it's main figureheads through history have been a mix of both Nords and Imperial races. The imperial race however is more of a mixed breed of Nibenese and proto-Nords. It's kind of a misnomer, and there's no need to associate them strongly with the empire itself. Do what you want.

Well the Empire was trying to execute you due to that you were caught in the same area with Stormcloaks, and I assume that the Thalmor Tullius was talking to in Helgen told him to execute everyone. It was nothing person, So depending on however you want to have your character story, like, If she is from Cyrodill and was raised with/to love the Empire, then she will still side with them. If she is just joining the Stormcloaks to kill the imperials for revenge, they may not let her in the Stormcloak army if they see your true intentions. Its up to you though.

Just make two separate files and join both sides. I joined the Imperials first as a Nord and the Stormcloaks as a High Elf -___- wasn't even thinking when I decided to choose my races and side.

I see no logical reason for you to join the stormcloaks. Make a nord if you want to do that i mean if you are playing another race and want to join the stormcloaks it would have to mean its cause you hate the Imperials and just made an alliance with the nords to kill them off.

I'm a tad biased in all of this.... but despite Ulfric Stormcloak's treatment of the Dunmer in Windhelm, I always pick Stormcloaks. Every damned time.
The Imperial army are cowards, and don't deserve support.

Why exactly iare the Imperial Army cowards?

I′d always join the Empire. I just can′t imagine myself fighting for the Stormcloaks and their ideals.

thats the first thing i recall walking into the storm cloaks capt. The soliders abusing that poor Dumer. I guess though that may not reflect Ulfric's view of them cause if he really didn't like them he could drive out the poor basteresd quicker then i can shake a fist. On the other hand, Ulfiric commited genicide and seems to be a power hungry mongrol who murdered Skyrim's high king. T

I think I will do this, I can see how the two different sides of war shape my character.