If you are looking for the tyGraph Pages Site Analytics Web Part when you try to add it to a page and you cannot find it, check the following.
Ensure you have installed tyGraph Pages Web Part package (tyGraphPagesWebParts.sppkg)
If you don't see the tyGraph Site Analytics web part in your list of web parts, you may not have installed the package. With tyGraph Pages you must install tyGraphPagesEngine.sppkg and tyGraphPagesWebParts.sppkg (Web Part Installation Guide). When you add the web part be sure and select Enable this app and add it to all sites. If you are using the classic App Catalog, check Make this solution available to all sites in the organization. While this step isn't required, it simplifies the installation process and you will avoid a number of potential issues.
You didn't choose Enable this app and add it to all sites
If you didn't add the app to all sites, the web part will not be available on a given site, unless you add the app to each individual site, you won't see it. Choose New -> App from the drop down menu on the home page of your site.
Now select From my organization and then tyGraph Pages Web Parts. Complete the process and you will be able to add the Site Analytics web part to any page on this site.
To save yourself from issues in the future, we recommend you uninstall the web part package from your App Catalog and then reinstall it with Enable this app and add it to all sites.
You installed to a single site collection and now you are using a different site collection
If you went against recommendations and you installed tyGraph Pages in a Single Site Collection, you will also have to repeat the process to install tyGraph Pages on every other site collection that you want to collect and report on data. Install the tyGraphPagesWebParts.sppkg package in the new site collection's app catalog and be sure you check Make this solution available to all sites in the organization.