Often on site where your order your electronics components you have an eagle library of component to download. As well big like sparkfun or adafruits - has own library of nearly all components that they propose on their site. But sometimes you need to create a new component based on the datasheet of component.
Let create new component MAX30100 that I did not found in any libraries in internet. Below is action plan.
First of all we need to find a datasheet of component that give us explanation of package sizes and connectors functionality that we will use to create our new library entry. Below you can see the 2 datasheet that I download from the vendor site that give me sizes of package and the pins description.
On this step you can eigter create a new library for your components or use one from existing. It up to you. I will use FabAcademy standard library and I will add a new component to it. To open a library - in main menu go to "File" section - then "Open" -> Library and select the library file you decided to modify.
As you remarked - in opened library we can see 3 different sections. Packages: in this section located all packages that can be used by different components (some components come in same package, like SMD resistors that we use comes in 1206 package, or attiny25,45,85 comes in SOIC8 package.) Symbol: is section that contain symbols that describe functions of element and that we use on principal schemas. And Device section where located description of element itself including the package and symbol (our final goal of this tip)
We will start by creation of new package. From Datasheet we see that package named "OLGA" - whatever it means we will use same name in our library because probably future components from same vendor may use similar package - so it may be reused in future. We start by creation of new package.
To draw package we need to set-up properly Grid (to simplify alignment of parts) and then we need use the draw smd / draw pad and so on tools to draw our package as it defined in datasheet. At the end use the "name" button to give some names to pins (it will be required to make a link in the future)
Now we create new symbol where we define the new component
Now we go to new device and we start compose it from already created symbol and package and make a link between them
We add a symbol and we add a description for our device
Now we add the package for our device. We select one we created early.
Now we need to make a link between the pins we created in Symbol and pins we named on our Package early. Just select one by one and click "Connect" button.
Now our component is ready to be used (of course we need to save library before close).
Let try to add it to real schematic. We can see component connected to other on principal schema.
And it has a normal behaviour and size on board schema.