Search for a solution
Thanks to the popularity of Arduino, it’s likely that the solution to your problem has already been documented somewhere. The key is to craft a suitable search query that is not too general, yet not too specific. For example, say you encountered this error:
C:\Users\rachel\Documents\Arduino\libraries\Adafruit_SSD1306/Adafruit_SSD1306.h:41:10: fatal error: Adafruit_GFX.h: No such file or directory
#include <Adafruit_GFX.h>
^~~~~~~~~~~~~~~~
compilation terminated.
exit status 1
Error compiling for board Arduino/Genuino Uno.
If you do a search for “Error compiling for board Arduino/Genuino Uno”, you are going to get thousands of irrelevant results because your search term is too generic.
If you do a search for “C:\Users\rachel\Documents\Arduino\libraries\Adafruit_SSD1306/Adafruit_SSD1306.h:41:10: fatal error: Adafruit_GFX.h: No such file or directory”, you won’t get any results at all because it’s too specific.
If you search for “Adafruit_GFX.h: No such file or directory”, you’re going to get a good number of results that are relevant to the problem. Likely you would find the solution to the problem within the first few results.
Ask for help
The excellent Arduino community is ready to help you with your problem. It’s very likely that someone is online now waiting to share the knowledge you need to get back to your project. But they won’t be able to answer your question if they can’t understand it. It’s essential that you provide enough information to help them help you.
Post the full text of any error error messages you’re getting. When you encounter an error you’ll see a button on the right side of the orange bar “Copy error messages” (or the icon that looks like two pieces of paper in the Arduino Web Editor). Click that button. The full text has now been copied to the clipboard, ready for you to paste it into your question.
If your problem is about code, post the full sketch.
Please always do an Auto Format (Tools > Auto Format in the Arduino IDE or “Ctrl + B” in the Arduino Web Editor) on your code before posting it. This will make it easier for you to spot bugs and make it easier for us to read.
If your code requires libraries that are not included with the Arduino IDE, post links to where you downloaded the libraries, or if you installed them via Library Manager (Sketch > Include Library > Manage Libraries) then state the full library name.
Don’t post pictures of text. This will make it more difficult for the people trying to help you. It will also make it so that others looking for help with the same problem later won’t be able to find your post in a web search.
Before posting, read what you wrote, pretending you are someone with no information about your problem other than what you wrote. Does it make sense? Is there missing information?
Study and follow the specific rules for the site you’re asking help at.
If posting to the Arduino Forum, please read and follow the “How to use this forum” guide: https://forum.arduino.cc/index.php?topic=148850.
Arduino Store Support
If your problem is related to a purchase from the Arduino Store, you can contact Arduino Store Support via this form: https://store.arduino.cc/store-support