Here’s a very quick primer to help you with it:
<img src="http://www.yourxyxwebsite.com/Images/SomeImage.jpg" />
Images folder in site root directory ("/")
<img src="/Images/SomeImage.jpg" />
Images folder in the current directory ("./")
<img src="./Images/SomeImage.jpg" />
./image.jpg and image.jpg are the same and refer to the current directory
Images folder in the parent directory ("../")
<img src="../Images/SomeImage.jpg" />
Root operator to identify root of the current application (~)
<asp:image runat="server" id="someImage"
We just saw that ~/ means the application physical root folder. However using this in the following format will not work on a webpage with a Master Page (ex: <img src="~/Images/SomeImage.jpg" />)
So instead use the Page.ResolveUrl() which translates an application relative URL to an absolute URL.
<img src='<%=Page.ResolveUrl(‘~/Images/SomeImage.jpg’) %>' />
Page.ResolveUrl converts the tilde ~ into the correct path for the current application directory.
I hope I have covered most of the frequently used paths. In case you have any doubts, just use the comments section to clarify them.