OpenShot is a free, open source, video editing program for Windows, macOS, and Linux. This software is great for editing and arranging large projects, applying title cards, and chroma key (green screen) replacement.
You can download OpenShot from https://www.openshot.org/. Launch the installer and follow the directions.
OpenShot comes with some title cards, but if you'd like to design your own you'll need to install Inkscape, a free, open source program for editing vector graphics. You can download Inkscape from https://inkscape.org/.
OpenShot can insert 3D transitions, but to do this you'll need Blender, a free, open source program for creating animation. You can download Blender from https://www.blender.org/.