If your pics are to large to host via TB.COM's manage attachments then you would use a host service. I am going to use photobucket as an example. Here are some instructions on how to host.
Log into your host service such as photobucket and follow these steps. Hope this helps.
Once logged in, click on my album then check the box of your uploaded pics. Here is an example:
Then it will give you options so click on generate img code. Here is an example:
Finally after generating the code, choose appropriate option and copy & paste it. I use the 4th one down for tb.com but it gives you options to host for email, forums, & such. Here is an example: