I presume from the presence of apt‑get that you are using Ubuntu or similar.
There is not necessarily any such file as install; rather it is an option you pass to apt‑get, followed by a space‑separated list of packages to install.
You should only run ./install if you are in a folder corresponding to a package (often zipped as a .tar.gz or similar) which has an install program/script. You tend to have configure and make instructions too. The details should be in a readme or similar file if you actually have such a package. Most packages have changed in the last few years, and can now be installed by simpler means.