To input a desired fixed lot size for each trade in an Expert Advisor (EA), you would typically need to modify the EA's code. The specific steps to do so depend on the programming language used to develop the EA. Here's a general outline of how you can approach this:

1. Locate the section of the EA's code responsible for trade execution or order placement. This section might include functions or methods related to opening trades.

2. Look for variables or parameters that control the lot size for each trade. These variables might be defined at the beginning of the code or within specific functions.

3. Identify the variable or parameter that represents the lot size. This is the variable you will modify to set the desired fixed lot size.

4. Update the lot size parameter to your desired value. For example, if you want to set the lot size to 0.01, assign the value 0.01 to the appropriate variable.

5. Save the changes to the EA's code.

6. Recompile the EA to ensure the changes take effect. This typically involves using the appropriate software or development environment for the EA's programming language.

It's important to note that the specific steps and variables involved may vary depending on the EA's code structure and programming language used. If you are not familiar with programming, it's advisable to consult with a developer or seek assistance from a knowledgeable source to make the necessary modifications to the EA.

Remember that setting a fixed lot size for each trade can have implications on risk management and position sizing. Ensure that the chosen lot size aligns with your risk tolerance and trading strategy.