Your TotalSend API username and password can be found once you log into your account
and click on the Settings > Integrations > TotalSend WordPress Plugin.
How can I display a TotalSend Subscription Form in my sidebar?
This can be done by configuring your TotalSend Integration widget within your WordPress installation. Once you have completed the installation procedure, and provided your TotalSend API credentials to the plugin, the TotalSend Integration Widget will provide you with an opportunity to select a list and any associated custom fields to be displayed on your WordPress site.
How can I display my TotalSend form in posts or pages?
This can be done by using the following shortcode totalsend-subscribe-form. However, this is after you have configured the plugin and associated widget.