how to use checkbox so when we click it it stay there code example

Example: only one of my checkboxes will check if i click on its label

<div>
    <label for="group">
        Select lists
    </label>
</div>
<div>
    <input type="checkbox" name="group" id="group1" value="1" title="Main List" />
    <label for="group1">Main List</label>
    <input type="checkbox" name="group" id="group2" value="2" title="Secondary List" />
    <label for="group2">Secondary List</label>
</div>