To import the MModding Library, you will need to add three mavens to your build.gradle repository block:

• The Maven Central (used by the Yumi Commons Dependency)
• JitPack (where you can find the MModding Library modules)

You would then have a repository block which looks like this:

repositories {
    mavenCentral()
	maven {
		name = "JitPack"
		url = "https://jitpack.io"
	}
}

And then, alongside Fabric API, you can the library in the dependency block:

dependencies {
    // Previous stuff. (like FAPI)
    implementation "com.mmodding:mmodding-library:${mmodding_version}"
}

Which would then require a mmodding_version property to be set in your gradle.properties file. You can find version numbers here.