Which version are you using?
Cloud
Go to Settings > Apps.
In the sidebar, under CONNECTOR FOR SALESFORCE, click Connections.
At the Salesforce Connections screen, click +Add Connection in the top right corner. If this is your first connection, the Connect with Salesforce panel appears, briefly explaining providing a brief explanation of the step and providing a link to more information. You can also click +Add connection here to open the Authorize Connection dialog.
The Authorize Connection dialog appears.
Enter a Connection Name, and select Production or Sandbox as the Salesforce instance environment type. Click Authorize.
If you're not logged into Salesforce, the browser loads a new Salesforce login page and prompts you to enter your Salesforce credentials.
If the authorization was successful, you can import the compact layout fields from Salesforce. This quickly pre-populates the objects and fields available through the connection.
This step is optional; you can always configure it later.Click Import to proceed.
When the authorization is successful, the Status changes to
.Status colour Green title authorized 
Server
This is a two-part process:
First, set an Integration User before you can create a Connection.
Add the Connection to Salesforce.
Step 1: Select an integration user
An integration user must create a dedicated Jira user account for this purpose. For more information, see Setting up an integration user.
Go to Settings > Add-ons/Manage apps.
In the sidebar, under CONNECTOR FOR SALESFORCE, choose Settings.
At the Settings screen, choose an Integration User for the Salesforce Package so that it can call Jira APIs on their behalf.
After selecting an Integration User, click Save.
Step 2: Add a new Connection
In the sidebar under CONNECTOR FOR SALESFORCE, choose Connections.
At the Salesforce Connections screen, click +Add Connection.
The New Connection dialog window appears.
Enter a Connection Name, then click Add.
The connection is added to the Connection Name list, but the Status shows as
.Status colour Red title not authorized Click Authorize under the Operations column.
Select the environment type of your Salesforce instance, either Production or Sandbox.
Click Authorize.
You will be given a code and asked to enter it at https://login.salesforce.com/setup/connect.
Note icon false 
When logging in to Salesforce to enter the code, the current user who logs in will become the "Salesforce Integration User".Follow the instructions. Once completed, return to your Jira instance and click Authorize.
If the authorization was successful, you can import the compact layout fields from Salesforce.
This will quickly pre-populate the objects and fields available through your created connection.
This step is optional; you can always configure it later.
Click Import to proceed.
When the authorization is successful, the Status changes to
| Status | ||||
|---|---|---|---|---|
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Next steps
If you are using Jira Server:
If you are using Jira Cloud: