How to Create or update Model in Dynamics 365?

In Dynamics 365, you can create a model with the wizard.

1- create Model

Open visual studio and go to Dynamics 365 > Model Management > Create Model.

specify the model name and publisher 

assign a description of this model and model display name (This is the name that’ll be seen in the Application Explorer in AOT)

Click next

Here, take care 

there are two options for development (overlayering or extensions  )

you can check this link for more details

https://docs.microsoft.com/en-us/dynamics365/unified-operations/dev-itpro/extensibility/customization-overlayering-extensions

Note:: recently Microsoft announced Customizations through extensions only in dynamics 365

check this link

http://dynamics365ax2012.blogspot.ae/2018/04/officially-customizations-through.html

so we can create a new package to develop via extensions not overlayering 

When you create a new package, you allow accessing the elements from any models  that we selected as the  reference

select referenced packages and click next

now, you can see the summary of your model

checked the create new project and make this my default model for new projects if you need.

click finish to create a new project

select dynamics 365 templates and assign a name to a unified operations platform project and solution name

click OK

you can see the project name on the left side and model on the right side under your solution

right click on your project and click add

you can add new item

or select exsiting item ( to upload item from local pc)

2-update model

You can update model parameter after creation as below 

and select your model that you need to update

update your parameters and click next to update package references

click Next to see the updated summary

click finish