we can use the Content Editor Web Part to add formatted text, tables, hyperlinks, and images to a Web Part Page in sharepoint. The Content Editor Web Part is intended for adding HTML content to a Web Part Page.It does not accept the HTML FORM element. There are three ways you can add content to the Content Editor Web Part: We can use the Rich Text Editor to type formatted content automatically without prior knowledge of HTML syntax. Click the buttons on the Standard and Formatting toolbars at the top of the window to enter and format the content. Click Help on the Standard toolbar to display a summary of the tasks that you can perform and their corresponding buttons.  we can use the Source Editor to enter or modify HTML source code. The Source Editor is a plain text editor and is intended for users who are familiar with HTML syntax.  Instead of editing content, you can link to existing content by entering a hyperlink to a text file that contains HTML source code.

1. Go to the sharepoint site page click Edit Page.
2. Choose a zone for the Web Part, and then click Add a Web Part in that zone. The Add Web Parts Web Page dialog box opens.
3. In the Add Web Parts dialog box, here select the media and content Web Parts, in the Default section, select the content Editor Web Part check box, and then click Add.

Here we can paste content directly or can use source code or Content Link copy the content from this site paste the content and click on save button, all html formats and css will come automaticaly