Part 1 - Taking a screenshot
The most common method to take a screenshot is one that has been built into the Android Operating System since about version 4 of Android.
To use this method hold down the power and volume down buttons simultaneously until your screen flashes and/or your device makes a noise similar to taking a photo, this should take about 1.5 seconds.
On some older phones this could be a different combination such as power button and home button, you will have to try it to know if it will work.
If the previous method didn't work for you then not to worry you can download an app that will allow you to take a screenshot, simply go to the Google Play Store and search for the app called Screenshot It, this app will allow you to take a screenshot.
Part 2 - Sharing your screenshot
Sharing your screenshot
Once you have taken your screenshot a notification will be created, simply swipe down from the top of the screen to display your notification drawer and tap the share button under the screenshot preview. You can then choose which app you want to send it to, this could be anything, for example if you want to email it you can select your email app and the screenshot will be attached to a new email.