put .gitignore in your main catalog

git status (you will see which files you can commit)
git add -A
git commit -m "message"
git push

I think the best solution is to generate .gitignore for yourself by gitignore.io.

Just choose tools that you used.

Disclaimer: .gitignores tend to accumulate entries over time and never have them removed; they're kind of cargo-cult files. It is not a bad practice to start with a minimal .gitignore in your project, covering only the tools you know and use, and add new entries when you become aware that they're required!

Here's some examples sourced from the .gitignore from the Nonprofit Success Pack, a very long-lived project that has seen many IDEs come and go, as well as a couple of other Salesforce.org projects. NPSP is built using a stack that includes Node.js and Python tools as well.

I've elided some entries that are obsolete or that I cannot explain.

Eclipse is end-of-lifed. You shouldn't have to worry about it anymore - if anyone on your team is still using Eclipse, tell them to stop!

.DS_Store                # Cruft from MacOS Finder
Thumbs.db                # Cruft from Windows Explorer

.project                 # I think this is Eclipse but not certain
.settings                # Ditto
salesforce.schema        # Eclipse
Referenced Packages      # Eclipse

build.properties         # Force.com Migration Tool

/IlluminatedCloud        # Illuminated Cloud
.idea/                   # IntelliJ IDEA (Illuminated Cloud)

venv/                    # Python
*.pyc                    # Python

.*.swp                   # Vim

*.sublime-project        # Sublime Text (used with MavensMate)
*.sublime-workspace      # Sublime Text (used with MavensMate)

.sfdx/                   # SFDX

.vscode/                 # Visual Studio Code

.cci/                    # CumulusCI

node_modules/            # Node.js (LWC, Prettier)
coverage/                # LWC coverage information
.localdevserver/         # SFDX/LWC dev

For excluding configuration files you have to configure .gitignore to something as follows:

# Eclipse
.classpath
.project
.settings/

# Intellij
.idea/
*.iml
*.iws

# Mac
.DS_Store

# Maven
log/
target/

And, only after this, you have to push your project because now you have to push your configuration to the remote repo.

And you can not delete it locally and push. You have to delete it from remote repo only:

git rm --cached .project

For a directory:

git rm --cached -r target