Salam. Don't know if Nayesha/nyesha, and Arissa are islamic names but I find in some web pages that Arissa means "bright" in arabic. Also, looking for the meaning of Umaira. I like the name Amaira but couldn't find any islamic connection.

Nayesha/Nyesha doesn't sound like any Arabic or Persian name I know of. Some sites say it is a Hindi name, but I cannot find any trustworthy sources for this.

Arissa, pronounced [(U)p] + [p(R)ay + sw(EE)t] + [(SA)nd], is a Persian girl name that refers to the flower known as Zanbaq in the Middle East, in English known as Iris. Both the Persian and English words come from the Greek word for "rainbow", since the flowers come in many different colors. Arissa is not an Islamic name but Muslims can use it since it has a good meaning.

For Umaira please see this page page: Umaira

As for Amaira, the only similar Islamic name is the girl name Amira.