Like others here, I will be assuming that you are on Windows.
Before jumping into LiClipse and PyDev, I highly recommend making sure that Python and packages (such as pip) are functioning on their own first. Command line is a great tool for this.
Windows Command Line can be accessed in a variety of ways, one of which is to go to your start menu and search "cmd." Command Prompt should return. In the command prompt, run the following:
python
This should return the version of Python installed on your machine if it is configured properly. For example, you may see the following:
Python 3.10.1 (...)[...] on win32
If this does not appear, I recommend uninstalling Python and reinstalling. In the installer, you will want to check the "Add Python ... to PATH" option. This will configure your environment variables on your machine. If you plan on running multiple versions of Python down the road, don't worry; you can use batch files to set the PATH variable to another version.
Once you have Python working, your command prompt will lead with the following:
>>>
Notice that there is no longer a file path followed by >>. This is because you are now in the Python interpreter. Congratulations!
To exit the Python interpreter, enter Ctrl+Z. It should appear as the following:
^Z
After we know Python works, we will check to see that pip works. Ensure you have pip installed by entering the following:
python -m pip --version
You should then be able to see the pip version. For example:
pip 22.0.3 from C:\...
If pip is not working, you can consult this documentation on pip to make sure pip gets installed properly.
Once pip is working, again, congratulations! You've gotten over some of the biggest hurdles. At this point, you can open up any text editor, type in:
print('Hello World!')
save the file with the extension .py, then run the script through command prompt. To run a script through the command line, you have to cd to the file location, then run the script with python, like so:
cd filepath
python filename.py
Where filepath is the path to the Python file and filename is the name of the file. For example:
cd C:\Users\name\Documents\PythonPractice
python helloworld.py
Usually, command line is all that is needed when starting out with Python outside of a text editor. Notepad comes standard on Windows computers, but there are plenty of other editors out there. Sublime text and Notepad++ are some of my favorites, personally.
Now, if you're able to run everything prior, the good news is that your Python and pip are both working, and you have everything you need to get started learning Python. If Python and/or pip are not functioning, there's thankfully a huge body of troubleshooting tips out there.
Unfortunately, from what I get of your initial post, you might be struggling with configuring LiClipse. I personally do not use LiClipse, nor do I use PyDev, so my help at this point may be limited. You may want to uninstall and reinstall after confirming your Python and pip work as a first step. After that, perhaps check that you are following the practices outlined in the LiClipse manual. Worst case scenario, you can try a different version of Python (I believe it has some Python3 incompatibilities), try running PyDev independent of LiClipse, or look at a different tool. If you believe the problem lies with file locations/existence, I would look at radj's post or play around in File Explorer to see what is going on for yourself.
Again, to get familiar with Python, you don't even need these extra tools. All you need is a text editor and the command line to get started.
Some other tools to help you get started:
PyPI
A venv virtual environment tutorial
PyDev
A comparison of LiClipse alternatives in case you continue to struggle
Hope this helps. Happy Coding!