Introduction: How to Install Optifine and Forge 1.14.4/1.15
The truth is that there is not yet a stable version compatible between the two major Minecraft tools, but if you really want to play with mods in version 1.14.4, there are some specific versions of forge and optifine that are compatible.
Step 1: Step 1
First upgrade your Minecraft to 1.14.4.
Step 2: Step 2
Download the forge by clicking here, go to the installer, proceed with the installation.
Step 3: Step 3
Open your Minecraft by selecting the installed forge profile. Then close it.
Step 4: Step 4
Go to start and open Run, look for: %appdata%\.Minecraft\mods
Step 5: Step 5
Download Optifine here, and drag it into this folder (Mods).
Step 6: Step 6
Once you have done these steps open your Minecraft with the forge profile again, it should open with optifine installed.