I just mixed together the gum-tex, glucose, and powdered sugar and set it aside to rest. My question is, Is it supposed to be a beige color or is it supposed to be white?

Hi, i use to make this , when i taught the g/p flowers at michaels. Now, we use the prepackage. the g/p you mixed is not white but the color you said. If you will use the prepackaged next time, you will never go back to making it. Trust me. I love wilton premade and or make nick lodges recipe, which is on the internet. hth
After you knead this you have made, it should be a little lighter in color, the best if remember.

Will it lighten up when i knead in the rest of the powdered sugar or do I need to add coloring to make it white?

I made this before and didn't like it because of the color. It seemed dull no matter what color I used (although I didn't try coloring it white). I stick with the premade now.

I make my own g/p and it always looks kind of ivory. It will dry completely white, but if you want REALLY white, you could always add white coloring to it. What I don't like is the smell.

Take the 40% coupon from Michaels or Hobby Lobby and go buy the Wilton pre-made stuff and save the other for projects that don't need to be pure white. I love this gum paste. It dries fast and very white.