Review the original item:
After the thunderstorm, Teresa splashed through the puddles left on the
street,
she enjoyed the cool rainwater on her hot feet.
You wanted to fix it this way:
After the thunderstorm, Teresa splashed through the puddles left on the
street,
because she enjoyed the cool rainwater on her hot feet.
A good way to fix a comma splice is to subordinate one of the two main clauses creating the error. Because, a subordinate conjunction, will often do the job.
You must remember one important thing, however. No comma is necessary before the because.
You might want to consult the rules for fixing comma splices and fused sentences.