From the Home tab in Setup, enter App in the Quick Find box, then select App Manager.
Click New Lightning App.
In the Lightning App Wizard, create an app with these parameters.
App nameDelivery Tracker
DescriptionTrack warehouse deliveries.
ImageYour choice!
Use a JPG, PNG, BMP, or GIF image that’s smaller than 5 MB. For best results, upload an image that’s 128 by 128 pixels. Images larger than the maximum display of 128 by 128 pixels are automatically resized.
Primary hex color value#09D4EA
App navigationStandard
Navigation bar items (in this order)Warehouses, Deliveries, Merchandise, Accounts, Contacts, Cases, Reports
Assigned to user profileSystem Administrator
Click Save and Finish to exit the wizard.
Click to open the App Launcher, and select the Delivery Tracker app.
Check out the new app! In case you find any other issue please mention. If you find your Solution then mark this as the best answer.
From the Home tab in Setup, enter App in the Quick Find box, then select App Manager.
Click New Lightning App.
In the Lightning App Wizard, create an app with these parameters.
App nameDelivery Tracker
DescriptionTrack warehouse deliveries.
ImageYour choice!
Use a JPG, PNG, BMP, or GIF image that’s smaller than 5 MB. For best results, upload an image that’s 128 by 128 pixels. Images larger than the maximum display of 128 by 128 pixels are automatically resized.
Primary hex color value#09D4EA
App navigationStandard
Navigation bar items (in this order)Warehouses, Deliveries, Merchandise, Accounts, Contacts, Cases, Reports
Assigned to user profileSystem Administrator
Click Save and Finish to exit the wizard.
Click to open the App Launcher, and select the Delivery Tracker app.
Check out the new app!
In case you find any other issue please mention.
If you find your Solution then mark this as the best answer.
>> https://trailhead.salesforce.com/content/learn/modules/lex_customization
You can try checking the above link for more understanding of creating and customizing the lightning app.
Let me know if it helps you and close your query by marking it as solved so that it can help others in the future.
Thanks.