This is easy to do and the following guide will show you how.
Login to your Twitter account.
Under the Options or your Logo Icon button in the top right of the menu click on Settings:
Your screen then changes view and you then choose Wigets from the menu on the left hand side:
If you do not have a widget yet then click on Create New.
Press Create New.
Then press Profile:
Then enter your Twitter Account URLas below:
Once you have entered your Twitter URL then press the little arrow.
You then hava a choice as to which format you are looking to embed:
From the above select which display you want to use. To show all your most recent tweets select Embedded Time line.
You are then given the option to set the widget size for how you would like it displayed on your website - allowing you to set the height and width in pixels - choose Set Customization options.
Then set the height and width you can set these to your own requirements and then click update to get the embed code:
Then as below choose Copy and you will be given the embed code to enter into your website.
Finally you are given the code which you can then copy into your website page source: