Integrating slices in a stack to a single image

Hello all,
A brand new ImageJ user. I am working on methods to increase image signal-to-noise ratio (SNR). The experimental data need long acquisition to get enough intensity, but the specimen always drifts. The drift deteriorates resolution a lot. One way to overcome this issue is to take a lot of frames with very shot exposure, then align them to remove the inter-frame drift (drift within each frame is ignored). Finally, sum the intensity of all frames to get a single image with high SNR and good resolution.
I imported the frames into ImageJ as a squence, and obtain the stack. Template Matching seemed to work to correct the drift (may be not perfect, but at least it seems the frames are translated somewhat). However, I cannot work out how to sum the intensity of the slices and save it as a single image. Could someone kindly give a hint to get it done?
Thanks a lot!

Z-project the stack using Image>Stacks>Z-project and use “Sum Slices” for the projection type.

Hi eljonco,
Many thanks! A lot of good stuff to explore in ImageJ.