My legs itch and are red after a shower does this mean I have sle?

No. It means you are sensitive to water, vibration, or heat. This is called aquagenic urticaria, a type of physical hives which can be controlled by pre loading with an non- sedating antihistamine. Cool compresses immediately after the shower will help as well as perhaps baths instead of showers.
Red, Itchy skin. Likely not. If you are truly worried and have close family relatives with lupus then you might feel better to get it evaluated. Hot water and hot showers are a classic cause of triggering the release of histamine in the body. Simply take cooler showers and don't stay in as long. If it continues, see an allergist since it could be something called dermographism.