How do I create a start page/homepage for my project

A start page can be specified in DataLion, which is visible when a project is opened. This homepage can be specified in the project settings in the "Content" tab in the "Homepage" sub-item.

The homepage is created using HTML and the code is inserted in the sub-item Homepage. More information you can find here.

A start page code can look like this - it contains a button that lies on a background image and links to the dashboard:

<style>
.largebutton {
width: 300px;
min-height: 100px;
background-color: rgb(117,0, 192) !important;
border: none;
font-size: 2em;
display:inline-block;
padding-top: 1em;
}
.modalbutton {
font-size: 1.5em;
margin: 10px 10px;
width: 90%;
}
</style>

<div class="row" style="background-image: url('Link to the Picture'); background-repeat: no-repeat; min-height: 1000px; min-width: 700px; padding: 0 2em">
<a href="Link to Dashboard"><h1 style="color:grey; font-size: 2.5em"; 
>To Dashboard</h1></a>
<div class="col-sm-12">
</div>

You can also limit yourself to a single link or just insert an image - as you wish.

More information about CSS and HTML can be found here.