Log in to your Altervista blog account. On your Dashboard click Edit to edit your site.
Look for place where you want to put your chatbox, left side on your screen, click Appearance under appearance, select Widgets
Under Widgets look for Text and drag to your desired area, Copy the "iFRAME code" on your chatwing account, Paste it on the Altervista and preview it, Adjust the size if necessary and make sure you click Edit HTML on the right side of the tab.
Save and view your website after publishing and enjoy chatting with friends and visitors.