Yahoo e-mail has been around a long time, since the 1990s. People with BellSouth and ATT accounts e-mail was moved onto using Yahoo e-mail ion the last year. This means there are lots of people using Yahoo e-mail now.
Attaching files (documents, spreadsheets, pictures, etc) is very similar in all e-mail systems but there are differences in each one. Basically in any e-mail system look for an Attach button when composing an e-mail or for Attach in one of the menus. Often a paperclip is the icon for attaching files.
In Yahoo e-mail you will click the Attach Files button. Then you will get a screen with 5 boxes and a Browser button beside each box.
Click on the Browse button and you will get the standard Windows Open box. You will then find the file you want to attach. Either on the left side you can choose the appropriate drive or using the drop down box. Then look in the folders for the appropriate folder. If the file is in My Documents or Documents then usually there is a choice to go straight there on the left. Once you have chosen the file click Open (this does not Open the file in the normal sense, but hakes it available to Yahoo e-mail).
Now you will see the path to the file followed by the file name in the box by Brose. If you have more files to attach do the same putting each on a separate line. You are not limited to 5 files, if you have more click Attach More Files at the bottom and more lines will appear.
Now for the piece a lot of people skip. Click the Attach Files button at the top. At that point the files are attached to the message and you will be back at the compose screen and will see the files listed at the bottom. Finish your message as normal and then click the Send button.
Realize when you send files that some e-mail systems limit the size of attachments (both individually and as a group on a message) and also know if the recipient is using broadband (DSL or cable type Internet connections) or dial-up connections. On dialup it will lock down their use of the Internet and take a while to download.
Thanks to Nikki for the question suggestion.