geNorm is more tricky: the core software is now integrated into qBase+, which is commercial, but the underlying maths is basic excel stuff, and the original genorm macro is available here:
Hey Rita! I would suggest you to download R (https://cran.r-project.org/bin/windows/base/) and R studio (https://www.rstudio.com/products/rstudio/download/) and then finally download the package CtrlGene (https://cran.r-project.org/web/packages/ctrlGene/ctrlGene.pdf) for performing GeNorm and BestKeeper analysis. It also gives you the power to make automatic graphs and stuff.
For NormFinder, you can find instructions here (https://moma.dk/normfinder-software) to use in R.